DECLARE @table_id AS INT
DECLARE @name_column_id AS INT
DECLARE @sql NVARCHAR(255) 

SET @table_id = OBJECT_ID('Contents')

SELECT @name_column_id = column_id
FROM   sys.columns
WHERE  OBJECT_ID     = @table_id
       AND NAME      = 'IsDeleted'

SELECT @sql = 'ALTER TABLE Contents DROP CONSTRAINT ' + D.name
FROM   sys.default_constraints AS D
WHERE  D.parent_object_id = @table_id
       AND D.parent_column_id = @name_column_id

EXECUTE sp_executesql @sql
GO

ALTER TABLE Contents DROP COLUMN IsDeleted 
GO
